This invention relates to a video signal recording circuit and the method adapted for maintaining a compatibility in reproducing between different video systems. More particularly, this invention relates to a luminance signal recording circuit and the method which is applied to the invention tilted "Improved video signal recording system" and disclosed in U.S. patent application Ser. No. 07/569,029, and filed Aug. 17, 1990 now U.S. Pat. No. 5,113,262, and adapted for compatibly reproducing a luminance signal from a video tape recorded by one improved video signal recording system in the order existing video signal recording/reproducing system.
The existing video signal recording/reproducing apparatus for home use records one video signals on a video cassette tape using one of several video signal recording/reproducing systems. Conventional video home systems(hereinafter referred to as standard VHS system) have insufficient horizontal resolution, leading to degradation of the picture quality. Generally, the improved VHS method referred to as super VHS(S-VHS) records or reproduces video signals of the full bandwidth on or from the video cassette tape and provides an improved image quality.
Such systems require good quality tapes and recording/reproducing apparatus. However, the above S-VHS system is incompatible with a video cassette tape recorder(hereinafter referred to as a VCR) of the standard VHS system. VCR of the S-VHS system is able to reproduce video tapes recorded by both the S-VHS and the standard VHS systems, but VCR of the standard VHS system is unable to reproduce video signals recorded by the S-VHS system.
Therefore, the above U.S. patent application Ser. No. 07/569,029 discloses an improved video signal recording system designed to provide a compatibility with the standard VHS system by obviating such conventional disadvantages as described above.
Especially, in the above system, when the adaptively folded signal passes through the pre-emphasis unit connected to the rear of the encoder, the folded high frequency components are emphasized along with the non-folded high frequency signal. Further, during reproducing such emphasized signals by conventional video signal recording/reproducing apparatuses, there is the disadvantage of degradation of the picture quality if a de-emphasizing process is not carried out exactly.
In other words, if the high frequency luminance components adaptively folded into the low frequency luminance components are amplified along with the non-folded high frequency luminance components as above, when reproducing the video signals by general video signal recording/reproducing apparatus, artifacts such as dot crawl are generated on the screen, lowering the quality of the image.